This application relates to an improvement in hybrid wrap scroll compressors wherein a suction pressure gas is passed through a thick portion of the wrap and between lower pressure and higher pressure compression chamber pockets. This gas cools the thickened portion of the wrap.
Scroll compressors are becoming wildly utilized in refrigerant compression applications. In a scroll compressor, a pair of interfitting scroll members each have a base and a generally spiral wrap extending from the bases. The wraps interfit to define compression chambers. One of the two scroll members is caused to orbit relative to the other, and as the two orbit relative to each other, the wraps compress an entrapped refrigerant in the compression chambers. The scroll compressor has become more successful due to the increased efficiency.
Originally, a scroll compressor wrap was formed of a generally uniform thickness, and essentially on an involute of a circle. More recently, and as the design of scroll compressors has become more sophisticated, so called xe2x80x9chybridxe2x80x9d wraps have been developed. In a hybrid wrap, the scroll wrap is defined by a complex curve, or even a series of curves. The thickness of the wrap also varies along a circumferential direction of the wrap.
In scroll compressors, the compression of the refrigerant generates a good deal of heat. Further, the scroll members are generally formed of a metal which is a good conductor for heat transfer. Thus, the scroll wraps will transfer heat from inner compression chambers radially outwardly to the outer peripheral surface of the wrap which may be in contact with the suction pressure refrigerant, and the suction pressure chamber. This is undesirable, and can result in efficiency losses.
Also, since the thickened portion of the wrap tends to have a good deal of contact surface, by heating the portion, other problems such as pinching, galling, etc. can occur.
In the disclosed embodiment of this invention, a cooling passage is formed through a thick portion of a hybrid scroll wrap. The cooling passage preferably communicates with suction pressure refrigerant, and extends entirely through the base of the scroll member. The cooling passage communicates suction pressure refrigerant through the wrap to the opposed interface between the wrap and the base of the other scroll member. Most preferably, this cooling passage is formed through the nonorbiting scroll.
The passage thus communicates low temperature refrigerant through a portion of the wrap which had served as a large source of heat transfer between the compression pressure chambers and suction pressure chambers. The passage thus acts as a heat barrier, preventing the transmission of the heat to the suction pressure chambers. This provides efficiency gains for the overall compression process.
Other benefits of this invention include the reduction of the contact surface area between the thick portion of the hybrid wrap and the opposed base. Also, the tip galling and pinching which has occurred with distortion of the thicker portion is also reduced. Further, by passing the lubricant carrying suction refrigerant to the interface, lubrication is provided to an area that has been somewhat difficult to lubricate in the past.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.